Schematic representation of pathways activated by M3 muscarinic receptors (M3MR) in astroglial cells. Shown in bold are those found in the present study to be involved in the neuritogenic effect of carbachol-stimulated astrocytes on hippocampal neurons. PLC, phospholipase C; PLD, phospholipase D; PA, phosphatidic acid; DAG, diacylglycerol; IP3, inositol 1,4,5-trisphosphate; PKC, protein kinase C; NF-κB, nuclear factor-κB; MAPK, mitogen activated protein kinase; PI-3K, phosphoinositide -3 kinase; PDK, phosphoinositide-dependent kinase.